I Neil deGrasse Tyson on Nikola Tesla and electromagnetic energy

[cnh1995]

I came across this video where Dr. Tyson talks about Nikola Tesla.
Neil Tyson on Tesla.
From 4:47 onwards, he says "We now send energy through wires", and talks about how bizarre it would be to walk around/stand in the way of such energy flow. Further he says the power transmission lines are suspended at some height/buried underground, have insulation etc so the people can't get "in the way" of the flowing energy.
With these statements, is he implying electrical energy actually flows "through" the wires? I understand that being exposed to EM fields is terrible for our health and why he is against Tesla's idea of sending energy through radio waves, but I am not sure what he meant by "sending energy through wires" stuff.

Maybe I am overthinking and missing his point?

 

[berkeman]

They are transmission lines being used to transport energy, yes. At low powers you mostly just transfer information on transmission lines. At high powers you transmit energy, and sometimes a little information.

And then there is Power over Ethernet (POE), etc.

 

[berkeman]

BTW, it's not completely accurate to say the power is being transported through the wires. It's more accurate to say that the energy propagates in the E and B fields generated by the voltage and current waveforms in the wires. At least for AC power transmission.

 

[cnh1995]

BTW, it's not completely accurate to say the power is being transported through the wires. It's more accurate to say that the energy propagates in the E and B fields generated by the voltage and current waveforms in the wires. At least for AC power transmission.

Yes that is what I thought.
Also when he freaked out about "standing in the way of energy flowing through air to power a lightbulb" , I thought of birds chilling on a high voltage transmission line conductor. When birds stand on a high power conductor, some energy must be flowing through their bodies as well, and they are not harmed (or at least not destroyed instantly!).
So I wondered whether he actually implied the energy is packed in the wires and transported instead of sending it through air.
Now I think I am being pedantic and focusing on the wrong part of the story!

 

[Dale]

some energy must be flowing through their bodies as well, and they are not harmed

That is correct. Energy flowing through your body does not cause harm. What causes harm is energy that is absorbed by your body. That is energy that flows into your body and not out.

 

[nasu]

The potential difference between two points a few centimeters apart on a cable with very low resistance is very small. Typical currents in high voltage power lines are given as few thousand amperes (I found 4000 A value quoted for the very high voltage lines) to few hundred amps in the secondary lines. The resistance of cables is given in the 30-60 mOhms/1000 ft range, which comes to micro-ohms per centimeter. If you touch the two terminals of a 1.5V battery while it powers an LED or flashlight you are "exposed" to a higher potential difference than the bird on the cable. Some "energy" goes through you though. But most of it gets to the flashlight.

 

[tech99]

If the power line frequency is very high, however, such that the spacing between wires is a significant part of a wavelength, then the bird will be exposed to electric fields acting along the wire.

 

[nasu]

But it is 60 Hz, isn't it? The wavelength is of the order of thousands of kilometers.

 

[vanhees71]

Maybe Teisen should study Poynting's and the other "Maxwellians'" achievements before producing youtube movies :-(.

 

[cnh1995]

Maybe Teisen should study Poynting's and the other "Maxwellians'" achievements before producing youtube movies :-(.

Yes, for someone with no/little scientific background, his choice of words and expressions would most likely imply energy is transported through wires, which is misleading.

 

[vela]

Yes, for someone with no/little scientific background, his choice of words and expressions would most likely imply energy is transported through wires, which is misleading.

How would you explain it to a lay audience without making their eyes glaze over?

 

[Dale]

How would you explain it to a lay audience without making their eyes glaze over?

Just say “along the wires” instead of “through the wires”

 

[vela]

Just say “along the wires” instead of “through the wires”

From the context I'm inferring from the OP, that seems like a pedantic quibble about word choice.

 

[Dale]

From the context I'm inferring from the OP, that seems like a pedantic quibble about word choice.

What more is needed than that word choice?

 

[hutchphd]

It's more accurate to say that the energy propagates in the E and B fields generated by the voltage and current waveforms in the wires. At least for AC power transmission.

So I wondered whether he actually implied the energy is packed in the wires and transported instead of sending it through air.

Maybe Teisen should study Poynting's and the other "Maxwellians'" achievements before producing youtube movies :-(.

Just say “along the wires” instead of “through the wires”

I feel certain that Dr Tyson is aware of the physics. Of course using any known technology would lead to rapidly diminishing energy flux with distance thereby requiring very large fields
The energy is of course guided by the wires to be a localized flux. As @Dale says. Not "in the wires"

 

[vela]

What more is needed than that word choice?

My point is that the intended audience for his video likely wouldn't notice the subtlety, so it doesn't really matter. Would it have been better if he said "along" instead of "through"? Sure, but it would mostly be so that people like us wouldn't jump to the conclusion that he's an idiot who doesn't know basic electromagnetism.